This invention relates to a lamp retainer ring and a lampholder assembly, for example, for individual lamps in a multilamp lighting system, such as a high intensity approach lighting system for an airport. More particularly, the invention relates to such a retainer ring and lampholder assembly which are effective in securing the lamp in the lamp housing even under severe storm conditions, and preferably in maintaining desired alignment even in the presence of jet blasts and high winds.
Many airports today, particularly those having Category II runways under Federal Aviation Administration (FAA) classification criteria, are equipped with a dual mode high intensity approach lighting system. Such a system provides visual approach lighting patterns to landing aircraft, and typically has a first high intensity approach lighting system mode and a second simplified short approach lighting system mode. The typical system is capable of providing 3000 foot patterns with any needed glide slope angle restrictions, and also shorter 2400 foot patterns for use on other domestic Category II runways, and includes both steady burning approach lights and sequenced flashing lights to provide directional guidance to the approaching aircraft. The steady burning approach lights are connected in a number of constant current lighting loops, and may be operated at several, for example, five, distinct brightness levels. Switching between the modes may be locally controlled from an adjacent substation, or remotely controlled from the air traffic control tower via a control subsystem.
In the first high intensity approach mode, the typical system includes approximately 100 lamps of the 300 to 500 watt type, connected in series in each of a plurality, for example, three, constant current loops. Additionally, fifteen flashers are active in a typical embodiment, so that the sequence will begin with the flasher farthest from the threshold of the runway and proceed toward the flasher closest to the runway threshold. Of course, the actual number of lamps and lamp wattage may vary for each loop of steady burning lights, and the number of flashers may vary for a specific application.
Such lighting systems are described in more detail in Manson U.S. Pat. No. 5,397,963, the disclosure of which is hereby incorporated in its entirety herein by reference.
The individual lamps of such multilamp lighting systems should be properly positioned initially and should maintain such proper positioning over time to provide highly effective system performance. In addition, the individual lamps should be easily and rapidly replaced when necessary to insure effective continuous operation.
Prior designs have stressed this rapid lamp change out feature. One such prior design employed a lamp housing holding a lamp. Compression loaded spring fasteners, secured to the housing, were passed through a plurality of individual spaced apart tabs which contacted the lamp and held it in the housing. Although this design allowed quick replacement of the lamp, it had a substantial problem. During severe storm conditions, which cannot be avoided because of the out-of-doors service in which such lamps are used, the lamps had an unacceptable tendency to fall out of the housings.
It would be advantageous to provide retainer systems and lampholder assemblies which are effective to hold a lamp in or to a housing and allow the lamp to be rapidly and easily replaced, when necessary.